Portable electronic devices such as personal digital assistants (PDAs), cellular phones, portable digital media players, and the like are becoming ubiquitous in modern technological societies. These devices offer specialized functionality in form factors small enough to carry in a pocket or some other small carrying bag. At least one reason why these types of devices are so popular is because display technology, which provides a convenient user interface, has advanced to a point where relatively small form factors are efficient and inexpensive. Indeed, even the most inexpensive portable electronic devices now include high frame rate color displays. However, conventional displays are not without some disadvantages.
Typically, a PDA may include a low resolution, high frequency (LRHF) display for displaying user selected information. One example of an LRHF display is a liquid crystal display (LCD). LCDs have many desirable characteristics including high frame rates which provide for a satisfying visual experience when rapidly switching between screens or when scrolling across a screen. However, high frame rates may, in some examples, sacrifice resolution. As an example, typical LCDs are configured to display images at a resolution of 130 pixels per inch (PPI) or less, which may result in “blocky” looking text and images. In those examples, small print may become difficult or impossible to read. In addition, readability may be affected by adverse ambient lighting conditions. Users of PDAs are familiar with the poor readability of LCDs under bright light or direct sunlight. In some examples, shading the screen or moving to a darker environment may be necessary to read an LCD.
In order to overcome the shortcomings of an LCD, high resolution, low frequency (HRLF) displays may be utilized instead of an LCD. One example of an HRLF display is and electronic paper display (EPD). EPDs utilize a material called electronic ink and are commercially available under the trade name E INK®. EPDs are ideally suited for flexible display applications due to their thin form factor and inherent flexibility. EPDs provide an image stable reflective display technology that uses ultra-low power but is easily read under any lighting condition including direct sunlight. In addition, EPDs provide a high resolution display and unlike LCDs, an image on an EPD looks the same from all viewing angles. Further, EPDs will not distort when touched or flexed, making EPDs the ideal display medium for flexible displays and portable devices. EPDs however, cannot, in many examples, completely replace LCDs. At least one reason is because EPDs typically have a low frame rate. As noted above, conventional LCDs are typically configured with high frame rates, which may serve to enhance a user's viewing experience especially when rapidly scrolling through multiple displays. In addition, using a mouse requires high frame rates so that the mouse pointer appears to have smooth movement across a screen.
It may, therefore, be desirable to provide a complementary display to conventional portable electronic device displays which provides a highly readable display that overcomes harsh ambient light conditions and that does not overly diminish battery life. As such, methods for controlling complementary dual displays are provided herein.